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<title>Fall 2002: Berkeley MIG Seminar Webcast Information</title>
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<h2><font size="+3">Fall 2002 Berkeley MIG Seminar<br>Webcast Information
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<font size="+1">Seminar Organizer: Professor Lawrence A. Rowe</font>
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<br><br><p>
The Berkeley MIG Seminar is held each Wednesday
from 12:00 (noon) to 1:30.
The seminar is webcast live on the Internet using a variety of technologies
(e.g., Mbone tools, Real Networks (RN), etc.).
The Mbone webcast includes two or
more streams so that remote viewers can see both the speaker and the slides
-- you can see a
<a href="user_view.jpg">screen dump</a> of an Mbone replay using the
Mash Collaborator tool.
The Real Networks webcast shows one stream so viewers typically download
a copy of the slides and follow along with the presentation. The slides
are published on the <a href="http://bmrc.berkeley.edu/bibs/mig">BIBS
seminar announcement page</a> (follow the link to the current speaker).
This semester we will also be producing two experimental transmissions
using NCast Telepresenter and RTPtv technology.
All of these technologies, with the exception of the RN technology, uses
the IETF standard for streaming media (i.e., RTP, etc.).
<p>
The architecture of the webcast system is shown in the following figure:
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<img src="webcastarch.gif">
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<br>
As you can see, all sources are sent to the <i>studio mbone</i>
multicast session. The actual broadcast is sent in the <i>webcast
mbone</i> session. We will use the Berkeley Access Grid Room for the
webcast session. The addresses for those sessions are:
<blockquote>
video: 233.2.171.195/59762/127
<br>
audio: 233.2.171.195/59764/127
</blockquote>
You can watch this webcast by using an Access Grid (AG) node or by launching
Mbone tools (e.g., vic and rat) on those sessions. An SDR announcement will
also be published that contains the following
<a href="MIG.sdp">SAP announcement</a>.
You might want to download a recent version of the
<a href="http://www.openmash.org/">Open Mash Mbone tools</a> so that you
can get the most recent version of <i>vic</i>. This version has new controls
for adjusting the layout of the thumbnail windows (e.g., just type a number
in the thumbnails window to change the number of columns and type an 's' to
enable scrollbars) and support to play the RTPtv high quality MJPEG stream.
<p>
We will use the AG MOO server for a backchannel
chat room. This room can be used both to comment on the production,
resolve transmission problems, and ask questions of the speaker. You can
use any MOO client by connecting to:
<blockquote>
venues.accessgrid.org/7777 (140.221.10.85)
</blockquote>
and going to the Institution Lobby and then to the UC Berkeley Room.
We use <a href="http://www.awns.com/tkMOO-light/">TkMOO-Lite</a>
for our chat interface tool.
<p>
The NCast Telepresenter stream can be viewed using another Telepresenter or
by using the Quicktime Player. We will produce an MPEG1 video stream
and PCM audio stream. The transmission will be sent in the
following multicast sessions:
<blockquote>
video: 233.2.171.195/11000
<br>
audio: 233.2.171.195/11002
</blockquote>
The following <a href="NCast.sdp">SDP announcement</a> can be passed to
the Qt Player.
<p>
We will also produce a production quality TV version of the stream using
the <a href="http://bmrc.berkeley.edu/papers/rtptv.html">RTPtv</a> technology
developed here at Berkeley. You can watch the video stream using Open Mash
<i>vic</i> or connect to the synchronized, low latency sessions using
<i>aclient</i> and <i>vclient</i> using the following sessions:
<blockquote>
video: 233.2.171.195/11000
<br>
audio: 233.2.171.195/11002
</blockquote>
For example, here are commands to launch the RTPtv tools
<blockquote>
vclient -M 233.2.171.195 -P 11000
<br>
aclient -M 233.2.171.195 -P 11002
</blockquote>
The <i>vclient</i> application can display on your desktop if you have the
correct X Windows server installed and you use the "-O" flag. And, remember
that if you have two LML cards in the PC, you need to select the correct one
if you have an external video monitor connected to it (i.e., "-1" or "-2").
Finally, we will also publish the studio mbone video session so that you
can see the other streams being produced locally. That session is:
<blockquote>
video: 224.2.1.5/22334/8
</blockquote>
Audio is produced into the broadcast session - that's why we have
the synchronization problem. The audio stream comes directly from the source
whereas the video stream is delayed and retimed by the Director's Console.
This should be solved by using NTP locally and using the a/v synch code
produced by rat, but we have had troubles getting it to work with Open
Mash <i>vic</i>.
<p>
Watch this space for further information about the webcasts.
<hr>
For further information contact
<a href="/people/larry/index.html"><i>Larry Rowe</i></a>
(Rowe at CS.Berkeley.EDU).
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